How do I remove UV images in Blender, and what do they do?
You can remove images(they are just simple images, not &quot;UV images&quot;, you usually create a &quot;UV Map&quot; and it's not an image, but a set of coordinates in a 2 dimensional UV space for your model's vertices that are in 3 dimensional XYZ space so you can use a 2D image to color or texture a 3D model) in the Outliner set to Blender File mode by right-clicking and choosing Delete:

Or by shift + left-clicking on the x in the Image Editor after you have opened the image. This will not completely delete it straight away, but will clear it's users meaning the image will not be saved with the file and will be gone the next time you open the file. The 0 before the name of the image indicates that it has no users and will not be saved. If you use the image somewhere else, like for example as a texture in some material, this action will also break things there as you will have a missing picture there.


What are the purposes of these images[?]

You are responsible for coming up with the purpose of the two image you have created, because you chose to create them. They can be used as textures, masks, you can paint on them or bake some material properties to them or do whatever you want with them.
The Render Result is meant to store current render when you want to render your scene. You should not worry about its existence too much and it will get created when you render something even if you delete it.